The Louisiana Purchase opened up the west and allowed people to move there and settle on the west side. The idea that influenced people to move west was the Manifest Destiny, which was the idea that the nation was meant to spread to the Pacific. Between the late 1830's and the 1860's more than 250,000 Americans traveled west. What attracted settlers to the west side was that there was more opportunity to farm fertile soil and enter the fur trade. A few east-to-west routes have been carved, by the 1840's. These include; the Oregon Trail, the California Trail, and the Santa Fe trail. All this over-land traffic effected the Plain Indians because they relied on the buffalo herds and they feared the buffalo would die off or migrate somewhere else. In 1851, to avoid conflict with the indians, the federal governent negotiated the Treaty of Fort Laramie.
The Three Trails: